The present invention relates to a function for generating a chord according to a key operation of a performer in an electronic musical instrument, and more particularly to an apparatus and method for exactly generating a chord corresponding to a key operated by the performer.
A general electronic musical instrument is a device for generating musical instrument sound corresponding to a melody played by a performer and comprises a keyboard means for receiving a melody specified by a performer and a sound source processing means for generating musical instrument sound according to key data supplied from the keyboard means. And, the electronic musical instrument additionally has auxiliary functions to automatically play a rhythm (drum sound) and a bass chord as well as the melody playing function so as to improve the performance effect and provide the performer with a convenient means of performing.
However, during the chord-playing mode, an electronic musical instrument generates the chord specified by the performer only when the performer inputs three or more constituent notes of the inputted chord, and converts the currently outputted chord into another chord only when two or more of the constituent notes of the inputted chord are different from those of the currently outputted chord. Accordingly, the conventional electronic musical instrument has problems in that the chord specified by the performer is not generated or a chord being different from the chord specified by the performer is generated. Such a problem is described with reference to the attached drawings as follows.
With reference to FIG, a conventional electronic musical instrument comprising a keyboard 10 for receiving constituent notes of a chord and a melody specified by a user, and a microcomputer 16 for receiving key data from the keyboard 10 is described. According to logic values of a rhythm selection signal supplied from a rhythm (drum sound) selection switch 12 and a bass selection signal supplied from a bass selection switch 14, the microcomputer 16 generates rhythm data, and melody sound data and chord data, both of which are processed from the key data supplied from the keyboard 10. In detail, when only the rhythm selection signal is in a high logic state, i.e., when the rhythm selection switch 12 is turned on, the microcomputer 16 assigns all keys of the keyboard 10 as a melody input portion, and generates melody sound data and rhythm data corresponding to the key data supplied from the keyboard 10. And, when only the bass selection signal is in a high logic state, i.e., when only the bass selection switch 14 is turned on, the microcomputer 16 assigns a part of the keys of the keyboard 10 as a melody input portion, and the other keys as a chord input portion, and generates chord data and melody data corresponding to key data supplied from the melody input portion and chord input portion, with rhythm data. Also, when both the rhythm selection signal and the bass selection signal are in low logic state, i.e., when both the rhythm selection switch 12 and the bass selection switch 14 are turned off, the microcomputer 16 assigns all keys of the keyboard 10 as a melody input portion, and generates melody data corresponding to key data supplied from the keyboard 10. To generate the chord data, the microcomputer 16 stores within its nonvolatile memory a chord table having chord type and a plurality of constituent-note key data according to a keynote of the chord type (i.e., according to a chord), and searches from the chord table the chord type and keynote having the same plural constituent-note key data as the three or more key data inputted from the chord input portion of the keyboard 10, thereby generating the performer-specified chord data by the searched chord type and keynote. Also, the microcomputer 16 does not generate chord data when two or less key data are received from the chord input portion of the keyboard 10, and does not change the previously generated chord data when three or more key data are received from the chord input portion and are not different in two or more keys from the previously inputted three or more key data.
The conventional electronic musical instrument additionally comprises a sound source circuit 18 for receiving melody data, rhythm data and chord data from the microcomputer 16. The sound source circuit 18 generates a rhythm signal having drum timbre by the rhythm data, and generates a musical instrument sound signal of predetermined timbre having predetermined pitch of note according to the melody data and chord data. The musical instrument sound signal and rhythm signal are filtered in a filter 20, so as to remove their unnecessary noise components. The filtered musical instrument sound signal and rhythm signal are amplified by a predetermined amplification rate in an amplifier 22 to sufficiently drive a speaker 24.
As described above, the conventional chord generating method does not generate a chord when a performer inputs two or less constituent notes of a chord, and does not change the chord when the currently input three or more constituent notes of chord are not different in two or more from the previously inputted constituent notes of a chord, thereby creating a problem in generating a chord different from that desired by the performer. And, the conventional chord-generating apparatus has a problem in that excessive memory capacity is needed to store the chord table composed of chord types and a plurality of constituent-note key data specified by the keynote, i.e., by chord names.